Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include<iostream>
#include<queue>
using namespace std;
int main()
{
	int h,w,a[55][55],d[]={0,1,0,-1,0},py,px,ny,nx,c=0;
	char m[55][55];
	queue<int>q;
	cin>>h>>w;
	for(int y=1;y<=h;y++)
	{
		cin>>(m[y]+1);
		for(int x=1;x<=w;x++)
		{
			a[y][x]=-1;
			c+=(m[y][x]=='.');
		}
	}
	a[1][1]=1;
	q.push(100);
	while(!q.empty())
	{
		py=q.front()/99;
		px=q.front()%99;
		q.pop();
		for(int i=0;i<4;i++)
		{
			ny=py+d[i];
			nx=px+d[i+1];
			if(a[ny][nx]<0&&m[ny][nx]=='.')
			{
				a[ny][nx]=a[py][px]+1;
				q.push(ny*99+nx);
			}
		}
	}
	if(a[h][w]<0)cout<<"-1"<<endl;
	else cout<<c-a[h][w]<<endl;
	return 0;
}